Brake



No. 607,852. Patented July 26, 1898.

E. w. e. c. HUFFMANN.

B R A K E (Application filed Dec. 29, 1897.)

2 Sheets-Sheet I.

(No Model.)

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No. 607,852. Patented July 26', I898. E. w. s. c. HOFFMANN.

BRAKE.

(No Model.) (Application filed Dec. 29, 1897.) 2 Sheets shee* 2.

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FFICEQ ERNST \VILHELM GUSTAV CARL HOFFMANN, OF CI'IARLOTTENBURG, GER-MANY, ASSIGNOR TO THE SIEMENS & IIALSKE ELECTRIC COMPANY OF AMERICA, OFCHICAGO, ILLINOIS.

BRAKE.

SPECIFICATION forming part of Letters Patent No. 607,852, dated July 26,1898.

Application filed December 29, 1897. Serial No. 664,389. (No model.)

To all whom it may concern..- Like letters indicate like partsthroughout o Beit known that I, ERNST WILHELM GUSTAV the differentviews.

CARL HOFFMANN, a subject of the Emperor Referring more particularly toFig. 1, the of Germany, residing at Charlottenburg, Gerbrake-shoe a,whose preferred construction 5 many, have invented new and usefulImprovewill be more fully hereinafter set forth, is susments in Brakes,(Case No. 94,) of which the pended by links I) from the body of the car,55 following is a specification, reference being the lower ends of thelinks engaging trun-, had to the accompanying drawings, forming nions c,projecting from the brake-shoe. The a part of this specification.brake-shoes are normally slightly removed My invention relates tobrake-shoes, and from the peripheries of the wheels. The coil has forits object the provision of an improved d of the brake-shoe may have oneof its ter- 6o brake shoe or block which may have a brakminals groundedthrough the wheels of the g 30131011 through the gen y 0f magnetism. carand the other terminal connected with a The invention, generallyspeaking, consists suitably-graduated resistance 6.

I 5 in a magnetized body of metal, or metal that An electric car isillustrated provided with is adapted to be magnetized, suitablysupatrolley conducting mechanism engaging the 65 ported beneath thecar-body, which through trolley-Wire f to convey current to the car. theagency of suitably-controlled means acts To apply the brake-shoe,current may be upon the wheel associated therewith to stop passed fromthe trolley conductor by means or retard its rotation. of thehand-switch 9 through the helix upon The preferred form of the inventionconthe shoe,which thereupon engages the periph- 7o sists in a brakeshoeprovided with a magcry of the car-wheel. The brake may alsonetizing-helix of wire, which is energized when be operated in otherways in addition to the it is desired to have the brake act upon theelectrical operation, in which case the brake wheel. I preferably mountthe brake-shoe so acts as a friction-brake if for any reason it is thatit will not only have a magnetic braking impossible to magnetize thebrake-shoe. action upon the wheel, but will also have Referring now moreparticularly to Figs. frictional contact therewith. 2, 3, and 4, thepreferred form of an electro- A car or vehicle may be equipped with themagnetic brake will be particularlydescribed.

3o brake-shoe of this invention in a manner to An oblong iron core h isprovided with a permit of the mechanical operation of the flange h,bolted at its periphery to aboX-like 8o brake, as heretofore, as well asthe magnetic iron body 2'. Aspace intervenes between the action, so thatin the event of failure of curcore h and the iron body 2', in which theen-- rent the brake may still be made to perform ergizing-helix d isdisposed. The core h is 3 5 its function. provided with three polarprojections h hi h The invention will be more readily underwhile theiron portion 1' is provided with four stood by reference to theaccompanying drawpolar projections t" z" t" i. The poles k z" are ings,which illustrate the preferred embodialternately disposed, a sufficientspace being ment thereof. provided between the poles to prevent the 40Figure 1 is a diagrammatic View showing magnetic flux from being shuntedfrom the an electromagnetic brake-shoe in position car-wheel. The facesof the poles opposed 0 upon a car and a circuit for controlling the tothe car-wheel conform in curvature to the action thereof. Fig. 2 is adetail sectional periphery of the wheel. The number of view of the brakeon line 2 2 of Fig. 3, a carpoles may be varied as desired.

45 wheel also being shown in elevation. Fig. 3 When the helix isenergized, polar regions is a sectional View on line 3 3 of Fig. 2, theof negative sign, for example, are formed at car-wheelbeingremoved.Fig.4is asectional 77, k 71 while polar regions of positive sign planview on line 4 4 of Fig. 1, the car-wheel are formed at 1 t" 'L '6. Whenthe parts are being shown in full plan. thus energized, the brake-shoewill be attracted toward the wheel and have frictionalengagementtherewith, theforce of this engagement depending upon the strength ofthe current. More or lesscircling magnetic lines of force are set up,according to the velocity of the periphery of a the wheel, each pointupon the periphery changing its polarity seven times in passing thebrake-shoe. When the speed of the wheel is slackened, these currents maybecome weaker, but the rim will be more thoroughly magnetized.Oonsequently the magnetic attraction will be increased, so that thebraking force, by properly proportioning the spaces between the poles,

may be made practically constant.

While the preferred embodiment of the in- Vention isherein shown andparticularly de- 1. In a brake-shoe, the combination with the magneticcore 72. provided with a plurality of poles h of a helix (1 surroundingsaid core,

and an inclosing magnetic mass i united with the core h, a spaceintervening between the core 71. and the mass '5 in which said helix isplurality'of polar projections i, the polar projections of the corebeing alternately disposed with relation to the polar projections of themass 2', the surfaces of the polar projections that are to be applied tothe wheel practicallyconforming in contour to the periphery thereof,substantially as described.

2. In a brake-shoe, the combination with two masses of magnetic metal,each having a plurality of polar projections which are adapted to engagea wheel, of an energizingheliX, the helix and magnetic masses being sodisposed that when said helix is energized polar regions of one sign areformed at the polar projections of one mass and polar regions of an.opposite sign are formed at the polar projections of the other mass, thepolar projections of one mass of magnetic material 7 being alternatelydisposed with relation to the polar projections of the other massof e

